Supramolecular Perylene Bisimide-Polysulfide Gel Networks as Nanostructured Redox Mediators in Dissolved Polysulfide Lithium-Sulfur Batteries

TitleSupramolecular Perylene Bisimide-Polysulfide Gel Networks as Nanostructured Redox Mediators in Dissolved Polysulfide Lithium-Sulfur Batteries
Publication TypeJournal Article
Year of Publication2015
AuthorsFrischmann, PD, Gerber, LCH, Doris, SE, Tsai, EY, Fan, FY, Qu, X, Jain, A, Persson, KA, Chiang, YM, Helms, BA
JournalChemistry of Materials
Volume27
Issue19
Pagination6765 - 6770
Date Published2015/10/13/
Abstract

Here we report a new redox-active perylene bisimide (PBI)-polysulfide (PS) gel that overcomes electronic charge-transport bottlenecks common to lithium-sulfur (Li-S) hybrid redox flow batteries designed for long-duration grid-scale energy storage applications. PBI was identified as a supramolecular redox mediator for soluble lithium polysulfides from a library of 85 polycyclic aromatic hydrocarbons by using a high-throughput computational platform; furthermore, these theoretical predictions were validated electrochemically. Challenging conventional wisdom, we found that pi-stacked PBI assemblies were stable even in their reduced state through secondary interactions between PBI nanofibers and Li2Sn, which resulted in a redoxactive, flowable 3-D gel network. The influence of supramolecular charge-transporting PBI-PS gel networks on Li-S battery performance was investigated in depth and revealed enhanced sulfur utilization and rate performance (C/4 and C/8) at a sulfur loading of 4 mg cm(-2) and energy density of 44 Wh L-1 in the absence of conductive carbon additives.